The present invention relates to oil circulation systems for internal combustion engines and particularly to the oil drain portions of circulation systems in air-cooled, overhead valve engines.
Harley-Davidson Evolution Model engines are of a 2 cylinder, air-cooled, gasoline (Otto cycle), 45.degree. V design of relatively large displacement and long stroke. These engines have overhead valves operated by push rods and rocker arm assemblies.
Large displacement air cooled engines, such as the Harley-Davidson Evolution Model, are usually constructed with finned aluminum cylinders having thin cast iron sleeves within which the engine pistons reciprocate. A separate cylinder assembly is provided for each piston in the engine and is attached to a crankcase body in corresponding alignment with the crank shaft.
If the engine is of an overhead valve design, as is the Harley-Davidson Evolution, some means must be provided to pump lubricating oil past the length of the cylinder and into the valve rocker assembly in the cylinder head unit. Return flow of that valve rocker oil is usually under gravity force through one or more conduits that are either cast or bored within the cylinder jacket wall alongside the cylinder sleeve. This jacket conduit necessarily has a mating conduit in the crankcase unit which returns the oil to sump or pump pick-up.
The interface between the cylinder jacket oil return conduit and the crankcase oil return conduit frequently is a source of oil leakage due to failure of a gasket seal with the juxtaposed sealing face surfaces respective to the jacket and crankcase. Usually, the leakage rate is not great since the fluid conduit is unpressurized. Perhaps it is more appropriate to characterize the loss as seepage rather than leakage. In many cases, such seepage only occurs at a certain temperature range in the engine cooling cycle. Frequently, no seepage will occur when the engine is hot and running.
Although there are many techniques for positive transfer of a hot, unpressurized engine oil stream across an assembly unit interface that would avoid any possibility of leakage, such prior art techniques are complex with external conduits and fittings or expensive with close tolerance machined surfaces.
It is an object of the present invention, therefore, to provide an inexpensively applied method of sealing engine oil return conduits.
Another object of the present invention is to provide an inexpensively fabricated apparatus for transferring oil in an engine conduit across an assembly interface without leakage.
Another object of the present invention is to eliminate persistent oil leaks from Harley-Davidson Evolution model engines.
Another object of the present invention is to provide a method and apparatus for eliminating engine oil conduit leaks in either new or old engines.